Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
501 am EDT Sat Apr 25 2015
low pressure tracking through Kentucky will provide chances for
rain and thunderstorms today and tonight. Drier weather will
arrive early Sunday and continue through the first half of next
week. While below average temperatures are expected today...a
moderation in temperatures will allow for more seasonable
conditions to return to the region early next week.
Near term /until 6 PM this evening/...
middle level low over the Central Plains to open up and and track
across the middle MS valley today and into the Ohio Valley tonight.
Associated surface low to move into the lower Ohio Valley by evening.
Weak area of isentropic lift has developed which has resulted in
scattered light showers.
As low approaches 40 knots low level jet develops...providing good axis of
low level forcing. Expect rain showers to increase in coverage with
the best coverage across the south. Marginal instability to develop across
the far south toward evening. Will go with categorical probability of precipitation across the
entire forecast area with chance of thunder south. Favorable low level shear will
exist in unidirectional deep westerly mean flow. Best instability and
shear looks to stay to our south but with warm front in vicinity of of our
far southern counties will continue mention of possible severe across the far
Precipitation will keep temperatures down today with highs from near
50 north to the upper 50s far south.
Short term /6 PM this evening through Monday/...
models solutions generally similar with surface low tracking east across Kentucky
tonight. Marginal instability to coincide with favorable unidirectional
shear across the far south ahead of the surface wave across the far south
late this afternoon and evening. As the low slides east-southeast precipitation will end
from northwest to southeast tonight into early Sunday.
Surface high pressure to begin to build southeast into the region Sunday. As
drier air and clearing develops cooler air will filter in. Lows
tonight to range from the upper 30s northwest to the middle 40s southeast.
Surface high pressure controlling our weather and northwest flow aloft...expect
to see a fair amount of sunshine. Highs Sunday to range from the
middle/upper 50s northwest to the lower 60s southeast.
Models showing a short wave rotating through the eastern Great Lakes Monday
around large upper low centered off the East Coast. Will maintain
a dry forecast with best moisture to the east but a sprinkle or light
rain shower is not out of the question. Temperatures still below
normal with highs on Monday from the upper 50s north to the lower
Long term /Monday night through Friday/...
high builds northwest of the region but gets caught up in the
muddled surface pattern and only a weak ridge is expected to nose
into the Ohio Valley for Tuesday.
Northeast flow at the surface will be found as the 500 mb pattern really
gets knocked around with weak ridges in between various troughs and
cutoff lows downstream of an entrenched ridge in the western U.S.
The mean longwave trough in the east will prevail and hamper any
significant warmup which would normally be expected with the higher
sun angles of this time in the season.
Interspersed periods of clouds during the daytime periods are
expected with a general warming trend as temperatures reach and slightly
exceed climatology normals by day 7 by tipping into the 70s.
A southern low pressure center in the mean 500 mb ridge may result in a
heightened threat of some light showers for the tail end of the
Aviation /09z Saturday through Wednesday/...
conditions are VFR to start. That will change as showers develop
and expand in coverage along a stationary front over Kentucky.
Greatest effects will be at cvg and luk where prevailing showers
with MVFR are forecast around 14z. Thunderstorms could occur in
the vicinity there late in the afternoon...followed by IFR
ceilings as low pressure moves along the front.
Farther north at day and iln...showers with MVFR are expected
from 14z through the evening hours...while cmh and lck may see
MVFR for a briefer period this afternoon to early evening.
Winds will be out of the east at about 12 knots by this
afternoon...shifting to northeast late in the forecast
period...with some gusts over 20 knots.
Outlook...MVFR ceilings possible Monday.